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Cystic fibrosis: terminology and diagnostic algorithms
  1. K De Boeck1,
  2. M Wilschanski2,
  3. C Castellani3,
  4. C Taylor4,
  5. H Cuppens5,
  6. J Dodge6,
  7. M Sinaasappel7,
  8. on behalf of the Diagnostic Working Group
  1. 1Department of Pediatrics, University of Leuven, Belgium
  2. 2Department of Pediatric Gastroenterology, Hadassah Medical Organization, Jerusalem, Israel
  3. 3CF Centre, Ospedale Civile Maggiore, Verona, Italy
  4. 4Academic Unit of Child Health, University of Sheffield, UK
  5. 5Department of Human Genetics, University of Leuven, Belgium
  6. 6Department of Child Health, University of Wales, Swansea, UK
  7. 7Department of Pediatrics, Erasmus MC-Sophia Children’s Hospital, University Medical Centre, Rotterdam, The Netherlands
  1. Correspondence to:
    Professor K De Boeck
    Department of Pediatrics, Pediatric Pulmonology, University Hospital of Leuven, Herestraat 49, 3000 Leuven, Belgium; christiane.deboeck{at}


There is great heterogeneity in the clinical manifestations of cystic fibrosis (CF). Some patients may have all the classical manifestations of CF from infancy and have a relatively poor prognosis, while others have much milder or even atypical disease manifestations and still carry mutations on each of the CFTR genes. It is important to distinguish between these categories of patients. The European Diagnostic Working Group proposes the following terminology. Patients are diagnosed with classic or typical CF if they have one or more phenotypic characteristics and a sweat chloride concentration of >60 mmol/l. The vast majority of CF patients fall into this category. Usually one established mutation causing CF can be identified on each CFTR gene. Patients with classic CF can have exocrine pancreatic insufficiency or pancreatic sufficiency. The disease can have a severe course with rapid progression of symptoms or a milder course with very little deterioration over time. Patients with non-classic or atypical CF have a CF phenotype in at least one organ system and a normal (<30 mmol/l) or borderline (30–60 mmol/l) sweat chloride level. In these patients confirmation of the diagnosis of CF requires detection of one disease causing mutation on each CFTR gene or direct quantification of CFTR dysfunction by nasal potential difference measurement. Non-classic CF includes patients with multiorgan or single organ involvement. Most of these patients have exocrine pancreatic sufficiency and milder lung disease. Algorithms for a structured diagnostic process are proposed.

  • CBAVD, congenital bilateral absence of the vas deferens
  • CF, cystic fibrosis
  • ICM, intestinal current measurement
  • IRT, immunoreactive trypsinogen
  • PD, potential difference
  • cystic fibrosis
  • lung disease
  • diagnostic algorithms
  • CFTR gene
  • sweat test
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  • Published Online First 29 December 2005

  • Funding: none

  • Competing interests: none declared.

  • Diagnostic Working Group: M Ballmann, Pediatric Department, CF Centre, Medical School, Hannover, Germany; I Bronsveld, Erasmus MC, Rotterdam, The Netherlands; H de Jonge, Erasmus MC, Rotterdam, The Netherlands; Y de Rijke, Erasmus MC, Rotterdam, The Netherlands; L Hjelte, Stockholm CF Centre, Karolinska University Hospital Huddinge, Sweden; T Leal, Université Catholique de Louvain, Brussels, Belgium; M J Schwarz, St Mary’s Hospital, Manchester, UK; I Sermet, Hôpital Necker-Enfants Malades, Paris, France; K Southern, Royal Liverpool Children’s Hospital, Liverpool, UK; B Strandvik, Göteborg University, Göteborg, Sweden; B Tümmler, Medizinische Hochschule Hannover, Hannover, Germany

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